The present techniques generally relate to systems and methods for allowing thermal expansion of electrolysis stacks during operation. In particular, a method for allowing differential thermal expansion of an electrolysis stack and a shell enclosing the stack is disclosed.
Electrochemical devices are useful in chemical reactions in which electrons may participate as reactants or products. For example, an electrolytic cell may use electrical energy to split lower energy reactants into higher energy products, which may then be used as materials, reactants, or in power generation. In another example, voltaic cells and fuel cells may be used to chemically combine higher energy products to form lower energy products, releasing electrons that may be used to power other devices. While in voltaic cells, the electrode may be consumed during the reaction, in a number of other electrochemical devices, such as electrolytic cells and fuel cells, the electrode is not intended to be a reactant, but merely to catalyze the reaction and collect or donate the current from the reaction.
Electrolytic cells may be useful in a number of processes, such as the splitting of water into oxygen and hydrogen in an electrolyzer. The hydrogen generated may be used in chemical processes, such as hydroformulation or hydrocracking in refineries, or may be stored for later use, such as in the generation of energy in a fuel cell. Electrolyzers may be assembled from a stack of individual plastic components that are joined together to form a contiguous structure, generally by adhesives or welding.
Generally, making the individual components from plastics is desirable, as plastics are both easily formed and insulating. However, the relatively high coefficient of thermal expansion for many plastics may be problematic. Electrolyzer stacks are typically enclosed in an outer shell, which may be made from metal. Although the outer shell protects the electrolyzer stack and provides reinforcement from radial or hoop stress, the outer shell may have a much lower coefficient of thermal expansion than that of the plastic. For example, the coefficient of thermal expansion for many plastics may be about two to four times that of many metals. Accordingly, techniques are needed to allow thermal expansion of electrolyzer stacks within metal shells, while keeping stresses placed on the electrolyzer stack low enough to prevent damage or failure.